What Else is Out there?

Abstract

Contrary to popular belief, the nine planets and sundry satellites are not the only lurkers in the region we call the solar system. As we have discovered in previous chapters, asteroids, comets, meteors, gases, and dust play important roles in the inner and outer system. (If we wanted to be more thorough, we could also add all the debris sent into orbit around the Earth from unmanned and manned space missions.) And there are more objects out beyond the farthest planet, some of them directly tied to the asteroids.

Keywords

Methane Dioxide Dust Mercury Titan

It is known to me that at least two American astronomers, armed with powerful telescopes, have been searching quite recently for a trans-Neptunian planet. These searches have been caused by the fact that Professor Newcomb’s tables of Uranus and Neptune already begin to differ from observation. But are we to infer from these errors of the planetary tables the existence of a trans-Neptunian planet? It is possible that such a planet may exist, but the probability is, I think, that the differences are caused by errors in the theories of these planets ...

Asaph Hall (1829–1907), professor and American astronomer, discoverer of Martian moons Phobos and Deimos in 1877.